Process of preparing 2-aminonaphthalene-3-carboxylic acid



Patented Nov. 6, 1928.

UNITED. STATES PATENTOIIF'FIYCE.

. ERNST HOTZ, OF HATTERSHEIM-ON-THE-MAIN, AND VALENTIN LANZ, OFHOCHST-ON- THE-IAIN, GERMANY, ASSIGNORS TO GBASSELLI DYESTUFFCORPORATION, 01' NEW YORK, N. Y., CORPORATION OF DELAWARE.

PROCESS OF PREPARING 2-AMINONAIHTHALENE-S-CARBOXYLIC ACID.

This invention relates to a process of pre-' paring 2 aminonaphthalene 3carboxylic acid.

We have found that 2-aminonaphthalene- 3-carboxylic acid of the formulaabout 90 per cent of the theory and in an easy and practical manner bysubjecting the products of reaction to the action of a bivalent ironcompound in such a manner that a complex iron compound, insoluble inwater and ammonia, is formed, and thereafter decomposing the complexiron compound into 2-amino-' naphthalene-3-carboxylic acid free fromiron. The formation of this new insoluble iron compound not onlyfacilitates the separation of the 2-aminonaphthalene-3 carboxylic acidfrom the reaction mixture but even promotes the formation of the2-aminonaphthalene-3- carboxylic acid, the equilibrium of the reactionbeing always displaced in favor of the insoluble iron compound and thefinished am-' inonaphthalenecarboxylic acid being protected against itsdestruction by any'secondary influences.

The insoluble iron compound is formed in an extraordinarily easy manner.The other metals of the iron group, i. e. nickel and cobalt, behave m aslmilar manner as '11011,

' whereas the other bivalent met ls such as zine, calcium, magnesium andcopper give no" compound corresponding to the abovementioned newinsoluble iron compound.

The simplest wayto introduce the iron required for the reaction is toadd it to the reaction liquid in the form of a ferrous salt, for

' instance ferrous chloride or ferrous sulfate,

whereby there is at once formed a colloidal precipitate of ferroushydroxide which is caable of further participating in the reaction.

t is also possible to add directly colloid ferrous hydroxide.

. Obviously the same iron com ound, but one of a lighter coloration, iso tained by simply adding metallic iron and ammonium chloride or sodiumchloride, or another chlo- Ro Drawing. Application filed December 16,1927, Serial No.240,627, and in Germany December 17, 1926.

ride which attacks the iron under the existing conditions in anammoniacal' medium with evolution of hydrogen gas. Like the chlorides,soluble salts with other anions for instance ammonium carbonateorammoniumsulfate will act in the same manner. The chlorides act, however,most energetically with being attended by the least secondary reactions.The formation of the iron compound depends on the presence ofbivalentiron. The metallic iron may be used in the form of iron turnings(filings or borings) or iron powder. The tendency of'form'ing the new,hitherto not yet described iron compound is so strong that in thepresence of chlorine-ions if no iron is added thereto the iron compoundis formed at the cost of the iron of the wall of the autoclave. The corrosion of the iron by the said salts in thepresence of ammonia isenormously increased by the presence of hydroxynaphthalene-carboxylicacid or aminonaphthalenecarboxylic acid which are thereby transformedinto the in soluble iron compound. In practice, when working with aniron autoclave, it is necessary'to avoid the addition of other chloridethan those of iron and to add a suflicient quantity of iron in theferrous stage, so as to prevent a detrimental corrosionof the walls ofthe vessel and the evolution of hydrogen.

According to our present invention one can conveniently work withammonia of 25 per cent strength or even of a lower percentage. Thereaction takes place between 150 C. and

250 C. the pressure varying from 30 to 60 sion for a reduction bynascent hydrogen.

Apart from this coloration, there could not be found any differencebetween the products or alkali. This surprising reaction in which theiron compound is formed, does not consist in a catalytic action of themetal salt, but in the stoichlometric formation of an iron compound with1 atom of bivalent iron to 1 molecular proportion of amino acid. Boththe results of analysis and the chemical properties of the new-compoundare at the present moment best explalned by the probable constitutionwithout warranting-the absolute correctness of this formula. The productcan certainly not be regarded as being a simple iron salt of theaminonaphthalenecarboxylic acid, for the normal iron salt of the2-amin0naphtha:

'lene-3-carboxylic acid described by Mohlau in Berichte der DeutschenChemischen Gesellschaft volume 28 (1895), page 3097, contains only atomof bivalent iron to 1 molecular proportion of aminonaphtalenecarboxylicacid'and is immediately decomposed in the cold by dilute acids oralkalies, also by ammonia, whereas the iron compound obtainableaccording to our present invention, contains 1 atom ofbivalent iron to 1molecular proportion of aminonaphthalenecorboxylie acid and can bedecomposed only by a prolonged heating with strong acids or causticalkalies, but not by ammonia nor in the cold. Ammonium2-aminonaphthalene- 3-c-arbonate'yields with ferrous salt the normaliron salt described by Mohlau, but by the addition of an excess ofammonia the latter is immediately re-decomposed into ammoniumaminonaphthalenecarbonate and ferrous hydroxide. When working, however,under pressure, there is obtained from aminonaphthalene carboxylic acid,ammonia and a ferrous salt a bod which is similar to the compound aboveascribed and probably identical withit. In the hitherto known reactionsin the domain of the aminonaphthalenecarboxylic acid there cannot befound an analogue to this iron compound. H

The following examples illustrate our invention, but they are notintended to limit it thereto. The parts are by weight.

1. A mixture of 100 parts of 2-hydroxy-- Q naphthalene-3-carboxylicacid, 150 parts of iron vitriol and 600 parts of ammonia of 25 per centstrength is heated in an autoclave provided With a stirrer for 20-30hours to 200 C. to 210 C. without having regard to c 3-carboxylic acid,the crude iron compound" (calculated upon 100 parts of starting2-hydroxynaphthalene-3-carboxylic acid) is boiled-for about 2 hours with1500 parts of moderately diluted hydrochloric acid (for instance in theproportion 1:4) and filtered hot. Only some charred substance remainsundissolved. The hydrochloride of 2-aminonaphthalene-3-carboxylic acidis salted out from the filtrate by means of common salt,

filtered in the cold and washed with a satu-v rated solution of commonsalt. The yield of the hydrochloride amounts to 85 to 90 per cent of thetheory. f Y

2. 110 parts-of sodium 2-hydroxynaphthalene-3-carboxylate, parts offerrous chloride, 500 parts of ammonia of 25 per cent strengthand 500parts of water are heated in a high-pressure autoclave for 24 hours to200 C. to 210 C. The pressure amounts to about 35 atmospheres.

After blowing off the ammonia the contents of the vessel is filtered.From the filtrate there can be separated by means of hydrochloric acid asmall quantity of unaltered 2-hydroxy-naphthalene-3-carboxylic acid.

The separated insoluble iron compound is boiled for 2 hours with 200parts of caustic soda solution of 40 B. and 800 parts of water, thenfiltered hot and subsequently washed with hot water. The free2-aminonaphthalene-3-carboxylic acid is precipitated in the filtrate inadding thereto hydrochloric acid until t ere is an acid reaction towardsCongo paper and neutralizin the free hydrochloric acid by means of soium acetate. The yellow acid is separated by pressing. The yield of2-aminonaphthalene-3-car-' boxylic acid amounts to 85 the theory.

3. 100 parts of 2-hydroxynaphthalene-3 carboxylic acid, 80 parts of.iron turnings, 80 parts of ammonium chloride, 500 parts of ammoniaof 25per cent strength are heated,

to 90 per cent of.

' while stirring for 24 hours to 180 C. to

1 probable formula:

190 C. in an autoclave lined with stones. 9

The ressure amounts to 40m 45 atmospheres.

A ter having blown off the ammonia and the hydro en which has beenformed, the contents 0 the vessel is filtered. The filtrate containssmall quantities of 2-hydronaphthalene-3-carboxyl1c acid.

The isolated yellow iron compound of the 2-aminonaghthalene-3-carboxylicacid, after being free in a mechanical way as far as possible from theiron which has not entered 1nto reactiomis mixed, while stirring, withparts of concentrated hydrochloric acid; the whole is heated to boiling,while well stirring, by passing steam through it, the boiling iscontinued for a quarter of an hour and the mass is then stirred in thecold. It is filtered while cold and washed with a saturated solution ofcommon'salt in. order to eliminate therefrom the iron salt which hasbeen formed during the decompositionproce'ss. The yield of thehydrochloride amounts to to per cent of the theory.

It is expressly stated that when working according to Example 3 it isdangerous to use an iron autoclave without stonehning because notoonlythe iron which is added but also the iron of the wall ofthe vessel isstrong- 7 ly'attacked b the action of the chlorine ions. After a num er.ofo'perations the destruction of the iron vessel and; the danger of anexplosionwould. be inevitable. The working methods according to'Examples 1 and 2, however, allow to use an ordinary iron autoclavewithout there being 'any' danger. Long ex perience has proved that thereis in this case no corrosion of the walls of the vessel.

The different working methods described in the preceding examples may,of course, be largely varied and combined.

In the following claims the term an agent capable of yielding bivalentiron ions is intended to comprise salts of the bivalent iron or mixtureswhichiare capable of yielding salts of the bivalent iron in the presenceof ammonia, such as for instance a mixture of metallic iron and ammoniumchloride, or the like.

We claim:

1. The process of preparing Q-aminonaphthalene-3-carboxylic acid byproducing the insoluble complex iron compound of the I i p i (no t anddecomposing thiscompound, soas to form 2-aminonaphthalenetl-carboxylicacid.

2. Theproeess of preparing Q-aminonaphthalene-3-carbox lic acid byheating a compound of the fol owing formula COOX wherein X stands forhydrogen or an alkali metal, with ammonia in a closed vessel in thepresence of an agent capable of yielding bivalent iron ions anddecomposing the insoluble complex iron compound thus obtained of theprobable formula: i

so as to form Q-aminonaphthalene-3 carboxylic acid.

4; The process of preparing 2-aminonaphthalene-3-carboxylic acid byheating 2.-hydroxynaphthalene-3-carboxylic acid with ammonia in a closedvessel in the presence of a ferrous salt and decomposing the insolublecomplex iron compound thusobtained of the probable formula: H l

v i Fo ll I so as to form 2 aminonaphthalene-3-carboxylic acid. x

5. The process of preparing Q-aminonaphthalene-3-carboxylic acid byheating 2-hydroxynaphthalene-3-carboxylic acid with ammonia in a closedvessel. in the presence of ferrous sulfate and decomposingthe insolublecomplex iron compound thus obtained of the probable formula: i H

man

so as to form 2-aminonaphthalene-3-carboxy lic acid.

6. The process of preparing 2-aminonaphthalene-3-carboxylic acid byheatin 2-hydroXynaphthalene-3-carboxylic aci with ammonia in a closedvessel in the presence of an agent capable of yielding bivalent iron ifions at a temperature between 150C. and

I droXynaphthalcne-3-carboxyhc 250 C. and decomposing the insolublecomplex iron compound thus obtained of the probable formula by treatingit with a mineral acid in the heat.-

7. The process of preparing 2-aminonaphthalene-3-carboxylic acid withammonia in a closed vessel in the presence of a ferrous salt at atemperature between 150 C. and 250 C. and decomposing the insolublecomplex iron compound thus obtained of the probable formula:

by treating it with a mineral acid in the-heat.

by treating it with a mineral acid in the heat.

9. 5 The process of preparing 2-aminona hthalene-3-carboxylic acid byheating 2- yacid with ammonia in.a closed vessel in the presence of anagent capable of yielding bivalent. iron v ions at 200 C. to 210 C. anddecomposing the insoluble complex iron compound thus obtained of theprobable forrnula by treating it with a mineral acid in the heat.

10. The process of preparing 2-aminonaphthalene-3-carboxylic acid byheating'2- hydroxynaphthalene-3-carboxylic acid with ammonia in a closedvessel in the presence of a ferrous salt at 200 C. to 210 C. anddecomposing the insoluble complex iron compoulnd thus obtained of theprobable fornm a:

I by treating it with amineral acid in the heat.

11. The prcess of preparing2-aminonaphthalene-3-carboxylic acid byheating 2-hydronaphthalene-3-carboxy1ic acid with ammonia in a closedvessel in' the presence of ferrous sulfate at 200 C. to 210 C. anddecomposing the insoluble complex iron com- 7 pound thus obtained of theprobable for,-

mula:

by treating it with a mineral acid in the heat.

12. The process of preparing 2-an'1inonaphthalene-3-carboxlic acid byheating 2- hydroxyn'aphthalene-3-carboxylic acid with ammonia of 25 percent strength in an autoclave provided with a stirrer in the presence offerrous sulfate for about 24 hours to 200 C. to, 210 C. and transformingthe insoluble complex iron compound thus obtained having the probableform ula:

if required after having it purified, into the2-aminonaphthalene-3-carboxylic acid by boiling it for about 2 hourswith dilute hydrochloric acid (1:4).

13. As a new product the compound ofthe probable constitution:

' said product being a crysalline compound [125 which, when heated forsome time with a concentrated or moderately diluted acid or causticalkali solution is transformed by decompositioninto,2aminonaphthalene-3-carboxylic acida '4 v i v In testimony whereof,we aflix our signatures. v

ERNST HOTZ.

- VALENTIN LANZ.

